High visual perceptual load reduces prepulse inhibition induced by task-unrelated and task-related sound.

Prepulse inhibition (PPI) is an automatic and pre-attentive sensorimotor gating process. Several studies have shown that advanced cognitive functions can modulate PPI. This study aimed to further elucidate the modulatory effect of attentional resource allocation on PPI. We examined the differences in PPI between high and low attentional loads. First, we verified that the adapted feature versus combination visual search paradigm could produce high and low perceptual load differences according to the task demands. Second, we measured the participants' task-unrelated PPI during the visual search task and found that the PPI in the high-load condition was significantly lower than that in the low-load condition. To further elucidate the role of attentional resources, we tested task-related PPI using a dual-task paradigm in which participants were instructed to complete a visual task with an auditory discrimination task. We found a result similar to that of the task-unrelated experiment. The participants in the high-load condition had less PPI than those in the low-load condition. Finally, we ruled out the possibility that the working memory load explains the modulation of PPI. In line with the theory of PPI modulation, these results suggest that allocating limited attentional resources to the prepulse modulates PPI. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Perceptual spatial position induces the attentional enhancement of prepulse inhibition and its neural mechanism.

Prepulse inhibition (PPI) is a sensorimotor gating process that reduces the startling response when a weaker sensory stimulus precedes a sudden startling stimulus. Perceptual spatial separation (PSS) between the prepulse and the background noise was found to enhance PPI compared to perceptual spatial co-location (PSC). However, little is known about the perceptual characteristics of prepulses in the PSS that induce more inhibition of the startling response and the associated neural mechanism. The dorsocentral striatum (DCS) was the convergence of spatial information from the cortical and thalamic circuits. Our study investigated whether the perceptual spatial position of prepulses induced spatial attentional modulation of PPI. In addition, whether the DCS was involved in spatial attentional modulation's neural circuits of PPI. In our study, the relative perceptual image positions of the prepulse and masker were controlled by the playback time difference between the two loudspeakers, i.e., PSS and PSC. The specific spatial attention of the prepulse was conditioned by foot shock. The results revealed that PPI was generally enhanced after fear conditioning/conditioning-control manipulation across all rats. Further enhancement of PPI in the PSS condition occurred only in the fear conditioning position, not in the conditioning-control position. We first found that PPI did not show specific spatial enhancement in the drug-blocking bilateral DCS rats with 2 mM kynurenic acid. These results demonstrated that the perceptual spatial position modulated the spatial attention of prepulse and improved PPI. DCS was involved in the attentional modulation neural circuits of PPI and processed spatial information of prepulse.